Seal-ring shape forming apparatus

A seal-ring shape forming apparatus by which a synthetic-resin seal ring is formed in a shape such that abutment joint ends of the seal ring face each other with a predetermined gap, the seal ring being molded such that the abutment joint ends are separated from each other, the abutment joint ends being provided at one point on a circumference of the seal ring and able to be joined to each other, the seal-ring shape forming apparatus comprising:

• an outer circumferential jig having a hole portion;
• and
• an inner circumferential jig that is disposed in the hole portion to form an annular gap between an inner circumferential surface of the hole portion and the inner circumferential jig, wherein a heating region and a cooling region are formed in the annular gap, the outer circumferential jig and the inner circumferential jig being maintained at a constant temperature higher than a glass transition temperature of a resin material for the seal ring in the heating region, the outer circumferential jig and the inner circumferential jig being maintained at a constant temperature lower than the glass transition temperature of the resin material for the seal ring in the cooling region, the seal ring is fitted into the annular gap while the abutment joint ends face each other with a substantially predetermined gap, and the seal ring is sequentially passed through the heating region and the cooling region to form the shape.